Absorbent articles for personal hygiene of the type indicated above are designed to absorb and contain body exudates, in particular large quantity of urine. These absorbent articles comprise several layers providing different functions, for example a topsheet, a backsheet and in-between an absorbent core, among other layers. The function of the absorbent core is typically to absorb and retain the exudates for a prolonged amount of time, minimize re-wet to keep the wearer dry and avoid soiling of clothes or bed sheets.
The majority of currently marketed absorbent articles comprise as absorbent material a blend of comminuted wood pulp with superabsorbent polymers (SAP) in particulate form, also called absorbent gelling materials (AGM), see for example U.S. Pat. No. 5,151,092 (Buell). Absorbent articles having a core consisting essentially of SAP as absorbent material (so called “airfelt-free” cores) have also been proposed (see e.g. WO2008/155699 (Hundorf), WO95/11652 (Tanzer), WO2012/052172 (Van Malderen)). Absorbent cores with slits or grooves have also been proposed, typically to increase the fluid acquisition properties of the core or to act as a folding guide.
WO2012/170778 (Rosati et al., see also WO2012/170779, WO2012/170781 and WO2012/170808) discloses absorbent structures that comprise superabsorbent polymers, optionally a cellulosic material, and at least a pair of substantially longitudinally extending channels. The core wrap can be adhesively bonded through the channels to form a channel bond, whose integrity is at least partially maintained both in dry and wet state. As the absorbent structure absorbs liquid and swells, the absorbent structure takes a three-dimensional shape with the channels becoming visible. The channels are indicated to provide improved fit and/or better liquid acquisition/transportation, and/or improved performance throughout the use of the absorbent structure.
The absorbent structures of the type disclosed above having channel-forming areas formed by attaching both sides of the core wrap through absorbent material free areas in the core have excellent wet fit properties. Indeed, whereas in conventional absorbent cores the weight of the absorbed fluid pulls the central part of the article down and causes a loaded diaper to sag significantly between the legs of the wearer, the core wrap bonds within the absorbent material area have been found to create longitudinal tension in the core that maintains the absorbent article in an upward state even when a significant amount of fluid has been absorbed. The inventors have now found that this effect may be detrimental for caregivers, which have learnt to associate the sagging of the article between the legs of the wearer with a high level of absorbed fluid and a signal for changing the article. Indeed due to the very high wet fit of the new absorbent structures, the caregivers may not recognize that it is time to change the articles.